Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UMLS:C0038187 (starvation)
 24,951 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The growth of the eucaryotic microorganism Dictyostelium discoideum in liquid culture was completely inhibited by the aspartic acid analog hadacidin (N-formylhydroxyamino-acetic acid). Growth arrest occurred both in chemically defined medium and in complex growth medium containing aspartic acid and AMP precursors such as adenine and adenosine. Although these compounds could not overcome the effect of hadacidin, growth was restored if cells were washed and resuspended in fresh growth medium. Additional experiments showed that D. discoideum contains adenylosuccinate synthetase, the enzyme which catalyzes the synthesis of adenylosuccinate from IMP, aspartic acid, and GTP in the de novo biosynthesis of purines. A partially purified preparation of this enzyme was obtained, and the effect of hadacidin on its activity was studied. We found that maximum inhibition of the D. discoideum activity occurs at a ratio of aspartic acid to hadacidin of 5:1, suggesting that the affinity of the drug for this enzyme is less than for the enzyme from rabbit muscle and plants but greater than for that from Escherichia coli. The effect of the drug can be overcome by a 10-fold excess of aspartic acid, suggesting that the drug acts as a competitive inhibitor. A comparison of the adenylosuccinate synthetase activity levels at various stages of growth showed that its specific activity decreases about 60% as cells enter the stationary growth phase, and decreases about 75% after starvation for 2 h. Further studies showed that in cells treated with hadacidin the rate of uptake of exogenous nutrients is reduced about 75% and that these cells are more resistant to rupture by osmotic shock. While the results of this study are consistent with the proposal that growth arrest is contingent upon inhibition of adenylosuccinate synthetase activity, they also suggest that, as a consequence of this inhibition, some physiological properties of the cell have been altered.
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PMID:Effect of hadacidin on growth and adenylosuccinate synthetase activity of Dictyostelium discoideum. 56 51

The elution profiles of Asp-tRNA from unstarved and starved cultures of a relaxed-control (Rel-) strain of Escherichia coli were compared by reversed-phase chromatography. Methionine starvation results in the appearance of several additional species of Asp-tRNA which are not observed with starvation for leucine or histidine. By the criterion of cyanogen bromide-effected shifts in chromatographic elution position, a large portion of the tRNAAsp synthesized in methionine-starved cells lacks the normal Q nucleoside. By the same criterion, virtually all of the tRNAAsp from unstarved, leucine-starved, and histidine-starved cells contain Q. We conclude that methionine starvation prevents the formation of the norma Q nucleoside in Rel- E. coli.
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PMID:Inhibition of nucleoside Q formation in transfer ribonucleic acid during methionine starvation of relaxed-control Escherichia coli. 110 5

Arterial plasma amino acids were measured in 27 patients with serious septic complications after operation, 15 patients following reduction of femoral shaft fractures and nine control patients on the first and third days following uneventful major abdominal surgery. Amino acid concentrations in the controls were similar to those which have been reported during early starvation. The amino acid patterns seen in all groups did not resemble that previously observed following glucocorticoid administration. In the patients with infection, mean phenylalanine concentration (108.0 +/- 46.9 mumoles per liter) was significantly greater than in the controls on the first (p greater than 0.001) or third (p less than 0.001) postoperative days. Four of the septic patients with hyperphenylalaninemia also had elevated arterial methionine concentrations. These observations suggest that many of the patients with sepsis had seriously impaired liver metabolism. In patients with fractures, the concentrations of ornithine (p less than 0.001), taurine (p less than 0.05), and aspartic acid (p less than 0.05) were lower than in controls. No other significant differences of amino acid concentrations were observed. It is difficult to relate these differences to a specific metabolic abnormality.
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PMID:Arterial plasma amino acids in patients with serious postoperative infection and in patients with major fractures. 125 95

We show that phosphorylation of the alpha subunit of eukaryotic translation initiation factor 2 (eIF-2) by the protein kinase GCN2 mediates translational control of the yeast transcriptional activator GCN4. In vitro, GCN2 specifically phosphorylates the alpha subunit of rabbit or yeast eIF-2. In vivo, phosphorylation of eIF-2 alpha increases in response to amino acid starvation, which is dependent on GCN2. Substitution of Ser-51 with alanine eliminates phosphorylation of eIF-2 alpha by GCN2 in vivo and in vitro and abolishes increased expression of GCN4 and amino acid biosynthetic genes under its control in amino acid-starved cells. The Asp-51 substitution mimics the phosphorylated state and derepresses GCN4 in the absence of GCN2. Thus, an established mechanism for regulating total protein synthesis in mammalian cells mediates gene-specific translational control in yeast.
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PMID:Phosphorylation of initiation factor 2 alpha by protein kinase GCN2 mediates gene-specific translational control of GCN4 in yeast. 173 68

Pancreatic procolipase is activated by trypsin forming colipase, a cofactor for pancreatic lipase involved in intestinal fat digestion and a pentapeptide named enterostatin. Enterostatin with the sequence Val-Pro-Asp-Pro-Arg (VPDPR) was previously shown to decrease food intake in rats both after peripheral and central injection. In this work enterostatin has been shown to reduce specifically the consumption of a high-fat diet as opposed to a low-fat diet after central injection of Sprague-Dawley rats. After starvation for 18 hours the rats were given a free choice of a low-fat diet (5.2% fat by weight; 14.1% by energy) and a high-fat diet (17.8% fat by weight; 32.8% by energy) in separate containers. After injection of 200 ng of VPDPR into the lateral ventricle, the rats selectively decreased the intake of the high-fat diet by 45% (p less than 0.005), while the intake of the low-fat diet was unaffected compared to saline injection. VPDP after intracerebroventricular injection had totally lost the selective effect on the consumption of a high- fat and a low-fat diet. It is suggested that enterostatin formed during fat digestion from pancreatic procolipase may provide a feed-back signal for the intake of lipid.
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PMID:Pancreatic procolipase propeptide, enterostatin, specifically inhibits fat intake. 189 1

In order to explore the possibility that, in autoimmune thyroid disease, anti-thyroglobulin (Tg) and anti-thyroid peroxidase (TPO) antibodies arise concurrently because they share a common T-cell epitope, we performed a detailed comparative analysis of the cDNA nucleotide sequences corresponding to these two genes. We discovered an 8 amino acid region (Leu-Ser-Glu-Asp-Leu-Leu-Ser- Ile in human TPO) in which there were 6 identical and 2 conserved amino acid residues when compared with human Tg. This remarkably similar region is near the amino-terminus of human TPO (residues 119-126) and the carboxyl-terminus of human Tg (residues 2763-2770). A second feature of interest was that this region of homology conforms to the Rothbard algorithm for a T-cell epitope. Third, probing of the Swiss-protein data bank (10,008 proteins containing 2,952,765 amino acids) with the human TPO region revealed greater homology for human Tg than for any other eukaryotic protein. Two bacterial proteins (E. coli aminopeptidase N and stringent starvation protein) had higher homology scores from human TPO than did human Tg. Our findings provide circumstantial evidence that human TPO and human Tg, and possibly certain bacterial proteins, do indeed share common T-cell epitopes that may play a role in the pathogenesis of autoimmune thyroid disease.
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PMID:Evidence for a potential common T-cell epitope between human thyroid peroxidase and human thyroglobulin with implications for the pathogenesis of autoimmune thyroid disease. 248 94

Aspartate transcarbamoylase labeled with 3-fluorotyrosine was purified from an Escherichia coli strain which was auxotrophic for tyrosine and overproduced aspartate transcarbamoylase upon uracil starvation. The labeled enzyme in which about 85% of the tyrosines were replaced by fluorotyrosine exhibited high enzyme activity that varied in a sigmoidal manner with respect to the aspartate concentration. Also, the labeled enzyme was inhibited by CTP, activated by ATP, and exhibited a 2.6% decrease in sedimentation coefficient upon the addition of the active-site ligand, N-(phosphonacetyl)-L-aspartate. Thus, despite extensive replacement of tyrosines by fluorotyrosine, the modified enzyme was similar to native aspartate transcarbamoylase. The 19F nuclear magnetic resonance spectrum of isolated regulatory subunits labeled with fluorotyrosine consisted of a single peak. Addition of the activator, ATP, or the inhibitor, CTP, caused a loss of intensity at about 61.3 ppm upfield from a trifluoroacetic acid reference and an increase at about 61.5 ppm, but CTP also caused an increase at about 61.0 ppm. Five overlapping resonances were observed in the 19F NMR spectrum of unliganded catalytic subunits containing fluorotyrosine. Although the binding of the bisubstrate analog, N-(phosphonacetyl)-L-aspartate, or the combination of carbamoylphosphate and succinate caused similar disappearances of resonances, the addition of N-(phosphonacetyl)-L-aspartate caused the appearance of resonances not observed with carbamoylphosphate plus succinate. Carbamoylphosphate alone perturbed three or four resonances and the subsequent addition of succinate affected at least two.
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PMID:19F nuclear magnetic resonance studies of fluorotyrosine-labeled aspartate transcarbamoylase. Properties of the enzyme and its catalytic and regulatory subunits. 404 74

The general control of amino acid biosynthesis was investigated in Candida spec. EH 15/D, using single and double mutant auxotrophic strains and prototrophic revertants starved for their required amino acids. These experiments show that starvation for lysine, histidine, arginine, leucine, threonine, proline, serine, methionine, homoserine, asparagine, glutamic acid or aspartic acid can result in derepression of enzymes. A correlation was found between the degree of derepression, growth of strains, and concentration of required amino acids. The amino acids pool pattern of mutants and revertants is different from that in the wild type strain.
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PMID:[General control of amino acid biosynthesis in mutants of Candida spec. EH 15/D]. 663 44

Pathways of L-glutamate and L-aspartate import by HeLa S3 cells were investigated before and after the cells were depleted of internal amino acids by starvation. Two new regulations of transport were observed in starved cells. Aspartate entered nonstarved cells by two routes, one non-saturable and one, an apparent analog of saturable system X-AG, that was sodium-dependent and competitively inhibited by glutamate. Starvation for one hour in saline increased the efficiency of saturable aspartate import, increasing Vmax and decreasing Km, an effect not previously reported for system X-AG. Glutamate uptake by nonstarved cells appeared to occur through system X-AG; through an analog of system X-C, which was sodium-independent, cystine- and quisqualate-inhibitable; as well as through one or more nonsaturable pathways. Starvation in saline for one hour resulted in the appearance of a new low-affinity saturable glutamate uptake system. This new system was sodium-dependent but not inhibited by aspartate.
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PMID:Novel regulations of glutamate and aspartate uptake by HeLa cells. 786 40

Measurement of amino acid concentrations in blood cells and plasma, and the calculated blood cell to plasma gradients (C/P) from both afferent and efferent vessels to tissues, allowed evaluation of the effect of several tissues (splanchnic bed, skeletal muscle and kidney) on blood amino acid distribution in fed and starved rats. Combined effects of tissues and erythrocyte transport capabilities determined specific C/P values for each amino acid. For amino acids related to the L-system, the high capacity of this erythrocyte transport many buffer some C/P changes as an effect of tissue metabolism. For less permeable amino acids (like Asp and Glu) plasma changes were mainly responsible for changes in C/P values, whereas for other amino acids (such as basic amino acids) blood cells became the main determinants of C/P changes, mainly in starvation. In general, the role of erythrocytes in amino acid transport was enhanced in starvation.
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PMID:Blood cell to plasma gradients of amino acids in arterial and venous blood in fed and fasted rats. 790 40


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